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  <h1>浏览器环境全局变量测试</h1>
  <script>
    var a = 'nihao'
    let b = 'llll'
    let c = {
      w: '789'
    }
    function fun() {
      console.log(a)
      debugger
    }
    function fun2() {
      console.log(b)
    }
    function fun3() {
      console.log(c.w)
    }
    fun()
  </script>
</body>
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